Underwater cables that are either suspended in or towed through the water require fairings in order to reduce cable strum and/or the drag force on the cable. Current underwater cable fairings are typically rigid streamlined foils or flexible grass.
The rigid streamlined foils provide good strum and drag reduction but are extremely bulky and difficult to store on a drum. Oftentimes, these cables can only be wound about a storage drum in one layer because of their bulk and interference by adjacent fairings on the drum. Thus, special handling equipment such as large drums are required to protect the fairings. Further, even if the fairings are made from a material having some degree of resiliency (e.g., plastic or rubber), storage on a drum often induces a permanent set associated with material creep stress relaxation. Then, when deployed, these fairings are unable to return to their intended shape which can result in hydrodynamic flow induced kiting of the cable. The current alternative to the use of rigid (or semi-rigid) foils is a flexible grass-like fairing. However, while being easy to store on a drum, these fairings have only successfully reduced strum at the expense of drag reduction.
Thus, there is a need in the underwater cable art for a cable fairing that reduces strum and drag, and a cable fairing that can be stored compactly on a standard storage drum without causing any permanent damage to the fairing's hydrodynamic flow characteristics. Accordingly, it is an object of the present invention to provide a fairing for an underwater cable that satisfies both deployed performance and storage criteria. Another object of the present invention is to provide a fairing for an underwater cable that may be fitted to existing cables. Yet another object of the present invention is to provide a fairing for an underwater cable that is inexpensive.